This application claims the priority of German Application No. 199 10 330.5, filed Mar. 9, 1999, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a system for monitoring a starter unit of a vehicle equipped with an asynchronous electrical machine serving as a starter and a generator, an inverter for converting the current generated or required in the electrical machine, and a control unit for controlling the operation of the unit consisting of the electrical machine and the inverter as a function of input signals. The control unit is capable of being activated at intervals also when the vehicle is not operated.
In the case of starter units for internal-combustion engines, the driver""s intention to start, as a rule, is reported to the starter unit by the closing of an electric contact, such as a switch. To avoid unintended movement of the vehicle, systems are known which permit starting only when, for example, the clutch pedal is depressed. In this context and with respect to related subjects, reference is made to International Patent Document WO 94/15808 and Japanese Patent Document JP 09042005 A. In these publications, systems are described which prevent an unintended driving-away in that they allow an engine start only under defined vehicle operating conditions, such as the operation of a clutch pedal.
In contrast, the present invention is aimed at a newer type of starter units for motor vehicles. In the case of these starter units, electrical machines are used which are operated as starters as well as generators. As an example, reference is made to crankshaft starter generators which have become known in the meantime. These electrical machines are connected by way of an inverter with an electricity supply system, to which consuming devices and batteries are, in turn, connected. For example, an electric valve gear may be provided as a consuming device. The electric valve gear has to be operated in an operationally reliable manner already during the starting operation. In the case of such an electric valve gear, but also in the case of other consuming devices, sufficient electric energy must already be provided during the starting operation. A control unit is used for this purpose. The control unit can be activated at certain intervals, also when the vehicle is not in operation, and tests the electrical condition of the vehicle power supply. However, during such an automatically occurring activation of the control unit, it must be completely excluded that the electric machine used as the starter is operated unintentionally and causes the movement of the vehicle, for example, when a gear is engaged.
It is therefore an object of the present invention to further develop a system of the above-mentioned type such that unintentional movement is excluded.
This object is achieved by a system for monitoring a starter unit in a motor vehicle equipped with an electrical machine serving as both a starter and generator, an inverter for converting the current generated or required in the electrical machine, and a control unit for controlling the operation of the unit consisting of the electrical machine and the inverter as a function of input signals. The control unit is also capable of being activated at intervals when the vehicle is not operating. An additional control function is provided, which activates or deactivates the inverter as a function of vehicle operating information.
Accordingly, an additional control is provided which activates or deactivates the inverter as a function of vehicle operating information. The linkage of the vehicle operating information as well as the release or blocking of the inverter can take place by way of software. However, the greatest safety is provided by a hardware circuit in the form of a driver. The inverter, which establishes the connection between the vehicle power supply and the electrical machine, will therefore only be activated if this is permitted by the vehicle operating information.
A rotational speed signal of the engine and a clutch operating signal may, for example, be used as vehicle operating information. In this case, the additional control is constructed such that the inverter is set to active only when either the clutch is operated or the rotational speed exceeds a defined value. This embodiment ensures that the electric machine, which becomes operative as the starter, can be started only when the clutch pedal is completely depressed. In addition, a continued operation of the electric machine is also possible without a clutch operation when a defined rotational speed of the engine has been reached or exceeded.
Naturally, instead of the clutch operating signal, other signals may also be used, such as a P/N signal of an automatic transmission. The signal must only ensure that the transmission line of the vehicle is interrupted so that, during the starting, a moving of the vehicle is prevented in every case.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.